The Probability of a Nuclear Accident

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Feature story - May 20, 2003

The nuclear industry and the Nuclear Regulatory Commission (NRC) have always maintained that the probability of an accident was low. However, neither the nuclear industry nor the NRC has been very good at estimating the probability of an accident.

The nuclear industry and the Nuclear Regulatory Commission (NRC)
have always maintained that the probability of an accident was low.
Even if we were to take the nuclear industry or the NRC at its
word, the risk of a meltdown would still be great because the
consequences of such an event are potentially so devastating.
However, neither the nuclear industry nor the NRC has been very
good at estimating the probability of an accident.

On March 9, 1979, the NRC staff produced a memo for then
Commissioner Peter Bradford entitled, "Probabilities That The Next
Major Accident Occurs Within Prescribed Intervals." The memorandum
states that:

The probability is less than .5 that the next (i.e., the first)
major accident occurs within the next 400 reactor years.

The probability is less than .05 that the next major accident
occurs within the next 21 reactor years.

The probability is larger than .5 that the next major accident
occurs after the next 400 reactor years. This is equivalent to
statement (a).34 (Note: one nuclear reactor operating
for one year equals a reactor year.)

Less than three weeks later, the unit 2 reactor at Three
Mile Island suffered a meltdown of the radioactive fuel in the
reactor core.

The Nuclear Regulatory Commission ignores the fact that
meltdowns have occurred at U.S. nuclear reactors. The NRC's latest
risk assessments don't even account for the meltdown at Three Mile
Island or the earlier meltdowns at Fermi-1 and other test reactors.
The U.S. nuclear reactors that have experienced partial core melt
accidents include:

EBR-1 (Experimental Breeder Reactor) 11/29/55 Idaho Falls,
ID

WTR (Westinghouse Testing Reactor) 04/03/60 Waltz Mill, PA

SL-1 (Stationary Low Power Reactor) 01/03/61 Idaho Falls,
ID

Fermi-1 10/05/66 Lagoona Beach, MI

Three Mile Island 03/28/79 Harrisburg, PA35

Even if you exclude the core-melt accidents at the test
reactors, the U.S. commercial nuclear industry has melted down two
nuclear reactors in less than 3000 reactor years. This reality
makes nuclear power anything but "safe." However, it wasn't until
after the Chernobyl disaster that the Nuclear Regulatory Commission
acknowledged the risk posed by nuclear reactors in the United
States.

In the wake of the 1986 accident at Chernobyl, the U.S. Nuclear
Regulatory Commission was asked to testify before Congress
concerning the potential for severe accident in the U.S. According
to NRC Commissioner James K. Asselstine:

...given the present level of safety being achieved by
the operating nuclear power plants in this country, we can expect
to see a core meltdown accident with in the next 20
years...36

The U.S. nuclear industry was quick to point out that you can't
have a "Chernobyl" here. Public pronouncements by nuclear industry
officials included assertions that Soviet technology was so
different from U.S. commercial reactors that the causes and
consequences of the Chernobyl accident had little relevance.
37 The American Nuclear Society's fact sheet on nuclear
energy stated that,."Because of major differences in technology, a
Chernobyl-type accident can not occur in a light water reactor such
as those in the U.S. A reactor similar to the Chernobyl design
could not be licensed in the U.S. either now or before the
accident." 38

Unfortunately, the nuclear industry was merely playing with
words. Their protestations rely on the fact that there are no
reactors of Chernobyl's design operating here in the United States,
but that's not the point. The reality is that a nuclear accident
can occur at a U.S. nuclear power plant that would have off-site
releases of radiation comparable to that of Chernobyl. Again in
testimony before Congress in 1986, NRC Commissioner James
Asselstine stated that:

While we hope that their occurrence is unlikely, there
are accident sequences for U.S. plants that can lead to rupture or
bypassing of containment in U.S. reactors which would result in the
off-site release of fission products comparable or worse than the
releases estimated by the NRC staff to have taken place during the
Chernobyl accident.

That is why the Commission told Congress recently that it could
not rule out a commercial nuclear power plant accident in the
United States resulting in tens of billions of dollars of property
losses and injuries to the public. 39

In 1990, the Nuclear Regulatory Commission was again asked the
probability of a severe core melt accident at a U.S. nuclear
reactor. However, the NRC refused to provide the National Academy
of Science's National Research Council with the number they were
seeking. In the Nuclear Regulatory Commission's response to the
National Research Council, the agency stated that it "would
strongly encourage your committee not to use any number based on
assuming an average severe core damage frequency…." Rather, the NRC
suggested that the National Research Council state that "there is
reasonable assurance that the health and safety of the public are
adequately protected." 40

At least on member of the NRC's Advisory Committee on Reactor
Safeguards (ACRS), doesn't hold the same overly optimistic view
espoused by the Commission. Hal Lewis, a former member of the NRC's
Advisory Committee on Reactor Safeguards, critiqued the
Commission's position when the ACRS was addressing the renewal of
nuclear reactor licenses, noting that:

The Commission certainly doesn't know that its current
regulatory process provides adequate protection to the public. It
has declared that it does, and it's the operating definition, but
the Commission has also promulgated safety goals and the commission
doesn't know that the current licensing basis will meet the safety
goals, although it believes it to be the case.
41

The public should not be lulled into a false sense of security
by the mere fact that the U.S. nuclear power industry has not
melted down a reactor since Three Mile Island. Operating without a
meltdown for a finite period of time does not mean that safety is
adequate. Again, Mr. Lewis, of the NRC's Advisory Committee on
Reactor Safeguards, recognized this fallacy. Mr. Lewis stated
that:

The general argument that the fact that one has
operated safely for a finite period of time proves that the safety
level is adequate is just not statistically right, because there
isn't that much history in the industry. And it's a trap. Because
other agencies, for example, people have used the argument that
they had 24 successful Shuttle flights, to show the level of safety
was adequate. And in retrospect, after one disaster, it turned out
not to be. The Soviets, after Chernobyl, suddenly discovered that
the level of safety they had before Chernobyl was not adequate. But
the day before Chernobyl they would have said it was adequate on
the basis of operating history..So it is a general trap, a
psychological trap, to believe that because something has not
happened, you are doing just fine. 42

The NRC and the nuclear industry have already fallen into the
trap. The NRC and the NEI have already begun to deregulate nuclear
safety regulations, including those dealing with the security of
nuclear reactors, based upon the limited operating history of
reactors in the U.S. The risk posed by nuclear power plants was
significant before September 11 th . When we take into
consideration the terrorist threat to nuclear power plants their
continued operation is unacceptable.

As NRC Commissioner Asselstine pointed out, U.S. nuclear
reactors are capable of releasing enormous amounts of radiation
into the environment. Since each reactor has the potential for a
Chernobyl sized release of radiation, it is important to recognize
the consequences of such an accident.

In 1990, the Wall Street Journal reported on a study conducted
by a Soviet nuclear industry economist on the continuing economic
disaster of the Chernobyl accident. The study found that the cost
of the disaster had originally been underestimated. Yuri Koryakin,
chief economist of the Research and Development Institute of Power
Engineering, the institute that originally designed the Chernobyl
reactor, found that the accident may cost 20 times more than
Moscow's original estimates. By 2000, the report estimated that the
Chernobyl accident would cost the country between 170 and 215
billion rubles from contaminated farm land, lost electricity
production and other economic fall-out. The accident contaminated
approximately 31,000 square kilometers or 12,400 square miles. When
the Wall Street Journal article was published in 1990, the
contaminated land was considered a total loss for at least two
generations. 43

The Wall Street Journal article concludes that, "The total bill
suggests that the Soviet Union may have been better off if they had
never begun building nuclear reactors in the first place."
44

The Nuclear Energy Institute (NEI) attempt to down play the
impact of the disaster. According to NEI:

The accident destroyed the reactor in Unit 4, killed 31
people (one immediately and 30 within three months) and
contaminated large areas of Belarus (formerly Byelorussia), Ukraine
and the Russian Federation. In addition, one person has
subsequently died from a confirmed diagnosis of acute radiation
syndrome, and three children have died from thyroid cancer.
45

The consequences of the accident are severely understated by
NEI. According to an article published by

the Associated Press the consequences of the Chernobyl
disaster are "grimly visible."

an estimated 4,000 deaths among those who took part in the hasty
and poorly organized cleanup; 70,000 people disabled by radiation,
according to government figures. Overall, about 3.4 million of
Ukraine's 50 million people, including some 1.26 million children,
are considered affected by Chernobyl, and many may not show the
affects for years. 46

The grim reality of the Chernobyl accident will be with the
people of the former Soviet Union for generations.

Shutdown Before Meltdown

The United States can avoid the next nuclear accident by phasing
out the remaining 103 commercial nuclear reactors. Rather than
coddling the nuclear industry with more taxpayer subsidies and less
regulation the federal government should replace nuclear reactors
with energy efficiency and other clean, renewable sources of
electricity.

A study conducted by the five national energy laboratories in
November 2000 for the U.S. Department of Energy found that
renewable energy could supply at least 7.5 percent of U.S.
electricity by 2010. 47 Such an expansion in renewable technologies
would allow for the phase-out of the most dangerous.reactors in the
U.S. When combined with increases in energy efficiency the
potential to phase-out nuclear power is even greater.

According to the Union of Concerned Scientists' Clean Energy
Blueprint, renewable energy could supply 20 percent of U.S.
electricity by 2020. 48 Coupled with an increase in
energy efficiency, this increase in renewable resources would
produce enough electricity to supplant every nuclear reactor
currently operating in the United States. 49

Rather than extending the licenses of nuclear reactors and
thereby extending the duration of the threat posed by these
reactors, the Bush/Cheney energy plan should heed the advice of its
own government laboratories and increase our nation's energy
efficiency and use of renewable sources of electricity.

36 Testimony of NRC Commissioner James K. Asselstine
before the Energy Conservation and Power Sub-committee of the House
Committee on Energy and Commerce, May 22, 1986; Also Letter from
NRC Commissioner James K. Asselstine to Carl Walske, President,
Atomic Industrial Forum, Inc., July 15, 1986, p. 1.

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